1. Talk presented at the Coral gables Conf. on Fundamental interactions at high energy;Fritzsch,1971
2. D.A. Dicus, R. Jackiw and V.L. Teplitz, Tests of light-cone commutator: Fixed mass sum rules, MIT preprint no. 207.
3. Proc. 3rd Coral gables Conf. on Symmetry principles at high energy;Dashen,1966
4. Equal-time commutators and dispersion relations